Wireless power transmission (WPT) often uses inductive power delivery, which is the use of non-radiating magnetic fields generated by a transmitter coil to induce a current in a receiver coil. Generally, for strong inductive coupling, the coils should be very close to each other. WPT is used in a variety of applications, and medical implants have used inductive power delivery for over 30 years.
The strongly coupled magnetic resonator (SCMR) has been used since 2007 (Kurs et al., Science 317(5834):83-86, 2007). SCMR systems show good efficiency and range, but they require a certain distance between the source and the resonators. Therefore, the traditional SCMR structures occupy a significant volume, making it difficult to use them for consumer electronic devices or medical devices.